1. Field of the Invention
The present invention relates to a flat and foldable, wallet-sized multi-functional electric appliance such as, for example, an electronic organizer, electronic telephone directory and schedule memo, electronic directory, electronic diary or electronic calculator, or an IC card reader. 2. Description of the Prior Art
A hand-held electronic calculator in its early days was a single-functional tool as its nomenclature speaks. It could not have all, but one function of performing arithmetic calculations, and the subsequent version had an added function of a clock. However, the hand-held electronic calculator currently placed on the market is available in a number of variants ranging from a traditional single-functional calculator to a sophisticated multi-functional calculator. The hand-held multi-functional electronic calculator is called in different ways, such as listed above, depending possibly on the manufacturer's marketing strategy and/or the way of use recommended by the manufacturer.
Although the present invention is applicable to any variant of electronic calculator, it is particularly concerned with the electronic calculator of a type which is of a size generally equal to that of a wallet or a checkbook clutch and is yet flat and foldable, comprising generally rectangular first and second flat casings hingedly connected thereof such that one of the first and second casings can be pivoted between folded and unfolded positions relative to the other of the first and second casings.
The flat and wallet-sized electronic calculator has a size limited in favor of the portability and is, on the other hand, required to have both an expandability of system functions and a multi-functional capability. An example of the prior art electronic calculator of the type referred to above is shown in FIGS. 5 to 7 for the discussion of the prior art relevant to the present invention.
FIG. 5 illustrates the prior art electronic calculator in plan view with the first and second casings held in the unfolded position, FIG. 6 is a cross-sectional view taken along the line A--A in FIG. 5, and FIG. 7 is an endwise view of the electronic calculator showing the manner in which one of the first and second casings can be pivoted relative to the other of the first and second casings.
As shown in FIGS. 5 to 7, the prior art electronic calculator comprises lefthand and righthand flat casings 1 and 2 of generally rectangular configuration pivotally connected together by means of hinge joints 3 each including a hinge pin 4. One of the lefthand and righthand flat casings, for example, the righthand flat casing 2, is pivotable, about a hinge axis defined by the axially aligned hinge pins 4, relative to the lefthand flat casing 1 between a folded position, as shown by the phantom line in FIG. 7, and a unfolded position as shown in FIG. 5 and as shown by the solid line in FIG. 7. The lefthand casing 1 has a card slot 6 defined at one end thereof for receiving therein a selected one of memory cards 5 and also has a function-expanding transparent touch-key pad 7, an I/F take-out mouth 9, a liquid crystal display 8, a lock knob 10 for locking the memory card 5 inserted into the card slot 6 and an eject knob 11 for ejecting the memory card 5 out from the card slot 6.
On the other hand, the righthand flat casing 2 has an inner surface formed with a plurality of keys 12 which are electrically connected with circuits in the lefthand flat casing 1 through a flexible connection 14 having a bundle of wirings. The functions available from the electronic calculator can be expanded by selecting one of the memory cards 5.
The electronic calculator when in use has its lefthand and righthand flat casings 1 and 2 spread open as shown in FIG. 5, however, the lefthand and righthand flat casings 1 and 2 are folded together when the electronic calculator is not in use as shown by the phantom line in FIG. 7 to enhance the portability.
While demands are steadily increasing for this type of electronic calculator to have added functions and also to have an increased storage capacity, the consequence is that the number of component parts tends to increase, accompanied by an increase of an electrical power consumption to such an extent that the electric power available from one or more coin-type flat batteries 13 such as, for example, lithium cells, would no longer support all necessary power requirements for a substantial period of time. Accordingly, the use of one or two AA-size batteries appears to be feasible, however, the prior art flat electronic calculator has no space for accommodating such batteries.
Where the high-capacity batteries are desired to be used in the flat electronic calculator, the electronic calculator must have an increased size and/or an increased thickness. Increase in size and/or thickness may result in a reduction in portability of the electronic calculator.
Other than the electric appliance shown in and discussed with reference to FIGS. 5 to 7, the Japanese Laid-open Utility Model Publication No. 62-147022, published Sept. 17, 1987, disclose a similarly flat and foldable electronic calculator comprising generally rectangular first and second flat casings hingedly connected at one side edge with each other. A battery chamber is defined along the opposite side edge of the first flat casing remote from the hinged connection so as to extend completely through the length of the associated flat casing. The provision of the battery chamber according to this publication has necessitated the use of the first flat casing having a width greater than that of the second flat casing by a distance corresponding to the outer diameter or width of the battery chamber.
Also, the Japanese Utility Model Publication No. 60-25618, first laid open to public on Feb. 21, 1981, discloses a hand-held foldable electronic calculator comprising generally rectangular first and second flat casings hingedly connected with each other in end-to-end fashion. Specifically, the first flat casing has a pair of annular hinge lugs protruding outwardly therefrom, and the second flat casing has a tubular housing integrally formed therewith. The first and second flat casings are hingedly connected together with the tubular housing sandwiched between and axially aligned with the annular hinge lugs, the tubular housing defining a chamber for accommodating a bundle of connecting wirings used to connect electric circuit parts in the first flat casing with those in the second flat casing, not for accommodating a battery, in a twisted fashion such that one of the first and second flat casings can be resiliently urged towards an unfolded position relative to the other of the first and second flat casings.